Wrist-pin lock



March 11. 1925. 1,530,097

` P. G. WAGNER ET AL WRIST PIN- LOCK Filed Sepp. 29, 1924 1 Patented Mar. 17, l925.

Urrea srarns ineen aar erica.

PAUL G. WAGNER AND ARTHUR ANDERSEN, 0F LOS ANGELES,- CALIFORNIA.

WRIST-PIN LOCK.

Application filed September 29, 1924. Serial No. 746,574.

To all 107mm t may concern."

Be it known that we, PAUL G. vWnennn and ARTHUR ANDnnsnN, both citizens Q the United States, and residents of the city of Los Angeles, in the county of Los Angeles and State of California, have invented new and useful Improvements in VVrist-Pin Locks, oit which the ollowing is a detailed specification.

rl`l1is invention relates t0 improvements in devices for releasably locking wrist pins within pistons or internal combustion engines and the like.

As is well understood, wrist pins comprise the connecting elements between pistons and connecting rods, and due to the vibratory stresses occurring at this point of connection, it is necessary to provide positive means for retaining the removable wrist pins from rotary and longitudinal movement.` Vhere the retention means is of a character to become loosened under vibration, the pins have a tendency to work out of the supporting piston bosses until the pin ends bear against the cylinder walls. As wrist pins are usually made et steeltheir end "engagement tends to cut grooves in the softer cast iron walls of the cylinders,a most harmful occurrence. Furthermore, loose wrist pins rapidly wear the piston bosses, and the resulting play or slap is very apt to have disastrous results, as is well understood by those skilled in the art.

Various types of wrist pin locks have been employed, most of'them in the form or set screws threaded through the piston bosses and projecting into seats or grooves in the wrist pins. However, these set screws tend to jar loose under repeated vibratory stresses, resulting in wrist pin looseness and its attendant undesirable results. It has therefore become customary to lock the set screws by such mea-ns as check nuts, Cotter keys, or the like, but due to the structural characteristics of pistons, it is a most ag-` gravating and tedious task to apply such lockine` means, and after their application they orten fail in their function.

@ther types of locking means, well known to those skilled in the art, depending, for instance, on wedge or spring action, are oiten employed, but they are all yOfcompartively low eiliciency, either due to their failure to hold or to the ditliculty of applying and removing them. They have the common disadvantage oit allowing wrist pin play the instant the locking means develop wear, this play rapidly increasing until it reaches t-he danger point, as outlined above.

Therefore, it is the principal object of our invention to provide a locking device which shall be positive vin its locking action and yet is capable oi2 being applied and removed with maximum ease. It is particularly applicable to hollow wrist pins, and the releasable means for retaining the lock member in position is located within the wrist pin bore. Then we provide means for automatically taking up all wear which may develop between the wrist pin and locking pin, aI feature of great value, as it constantly maintains the locking device fully effective throughout the period ofl its useful life. v

A better understanding of `the`invention will be had from the following detailed description,reerence being made tothe accompanyingl drawings, in which:

F ig. 1 is a sectional view of a piston showing a wrist pin locked therein by our device; v f

Fig. 2 is an enlarged section, partly lin elevatiointakenfon line 2 2 of Fig. 1;

Fig. 3 is a section, partly in elevation, on line 3-3 or' Fig. 2;

F ig. et is a view similar to Fig. 2 but showing a modilied form ci? locking device;

Fig. 5 is a View similar to Fig. k2 but showing another modiied form of locking devi-ce; and v Fig. 6 is a' sectionon line 6 6 of Fig. 5.

In vthe drawings, numeral 10 designates a piston having diametrically opposed, internal bosses 11 and 11l which provide end support for hollow wrist pin 12.

Connectingrod 13 has bearing on pin 12 in theusual manner.` Our locking device may be appliedtopin 12 at either or both ends, but we find that its application to but one .endv suii'ices to securely lock the wrist pin, and We have therefore illustrated and will describe it only in connection with boss 11.

Boss 11 has a depending,projection l111` having a bore l5 which extends radially with respect to boss bore 16, While pin 12 has an aperture 17 preferably` of smaller diameter than bore 15 but adapted to be brought into axial alinenient therewith when the wrist pin is in operative position within the piston.

A tubular locking pin 18, having a linger grip flange 19 has sliding fit within bore 15 and has a tapered inner end'20 adapted to seat within wrist pin aperture 17 and to maintain said` aperture in axial alineinent with boss bore 15.

Longitudinally slidable through the bore of locking pin 18 is a plunger 21, one end thereof, being headed while the otherend is adapted to extend through vaperture 17 and to project into wristpin bore12a.

' Preferably, though not necessarily, pin 18 is counterbored at 24: to provide a pocket tor spring` 25, said spring encircling plunger 21 and being interposed between plunger the bore of pin 18, spring 25 yieldably resist-k ing this telescopic movement to such an cxtent that considerable pressure is needed to thrust .plungereiid' 23 into pin '.bore 12a. Plunger 21 is moved inwardly until notch 27 is fullypresented within bore 12, whereupon key A28 istpassed through the ope-n end ot bore 12a andfslipped through notch.A 27 into the'position illustrated. Manual pressure on plunger 21 is then relieved, and

spring 25 acts to draw, plunger end 23 into key notch 29,`wings 29a at either side 'of the notch preventing longitudinal displacement of the key.

Key 28 prevents accidental withdrawal ot plunger 21 and hence pin 18, and spring 25 Y both holds key 28 in engagement with the wrist pin and draws pin taper 2O into irm seating engagement with the wrist pin to prevent both longitudinal and rotary move- `nient of said pin with respect to boss 11.

Of course, the described procedureV of assembly need not be rfollowed exactly. For instance, pin 18, plunger21 and spring 25 `may be assembled exteriorly oit' the piston and thrust, as a unit, into operative position.

Spring 25 constantly urges taper 2O into seating engagement with the wrist pin to take up any wear which may develop between the locking device and the wrist pin.

The spring also takes up ,wear developingin the locking elements themselves, with ob` vious advantage.

In order that there may be no interference' 17 to allowthe positioning of key 2t between pin 18 and key 28, tapered end 2O is notched at 31. Of eoui'se, when end 2O is not of suflicientlength to extend into bore 12, notch 31 need not be provided.

It is not necessary that bore 15 and aperture 17 bey in exact axial alinenient when the locking device is attached; it is only necessaryA that they be in such alinenient that plunger 29 may he thrust through aperture Then, when the piston is jarred or reciprocated,

vtaper .20. will be gradually moved through aperture '17 by Spring 25 and will finally bring said aperture into axial alineinent with ,bore 15. i

1n Fig.v 4 we have shown a modified torni of lockingdevice wherein locking piu 18" is solid` and has no movable plunger cori'espending to 21. The reduced end 32 oic pin 18 is slotted at 38 similarly to the end of plunger 21,*the slot being adapted to receive key 28, similar to kcy28. Spring 25" encircles pin 18 and is interposed between pin head 19 and boss projection shoulder 34. Pinl 18l is adapted to extend through boss bore 15 to bring end 82 through wrist pin aperture 17, spring 25 and key 28"L serving to hold pin 18a from longitudinal displacement.

In Figs. and 6 we have illustrated n inodihed torni of plunger and key. Such parts as are similar to or have the function of correspon-ding parts ot Fig. 2 are nunibered similarly except thatthe reference numerals otFigs. 5 and 6 are given vthe exponent b.

Plunger 21b` has an annular head 35, and after tubular pin 18h, plunger. 21b and spring 25b have been assembled, head 22b is riveted in place against plunger'shoulder 36 to hold the severalelements in assembly.

Key 28b is in the torni of a disc which is drilled at 87 t0 receive the shank ot plunger 21b and counterbored at 88 to receive plunger head 8,5. Slot) opens to bore 8T so, after they locking device has been entered in apertures b and '17h and after the plunger has been thrust upwardly a sufficient dis` tance into bore 12c of wrist pin'12", the key may be slipped beneath plunger head 35.

'Then when the manual pressure on the plunger is relieved, spring acts to draw plunger 21"l downwardly, seating head 35 in countersink 88 to hold the k-eyagainst accldental displacement. The key functions iu the saine manner as key 28, but since its lower, Afiat face is spaced above. aperture 1T" (due to the arcuate. characteristic ojl" the deining wall of bore 12C) tapered end 2Gb oit pin 18b need notV be slottednor notched even though said end projects slightly into bore12c.

vIt will be understood that various changes iii-design, structure and arrangement may -be madewithout ydeparting trom the spirit and scope of the appended claims, and there-pin aperture, and yieldable means between in a piston boss,

tore we do not wish to be limited except for such limitations as a fair interpretation of said claims may import.

Having described a preferred form ol our invention, we claim:

l. In a device for locking hollow wrist pins in piston bosses, a locking pin adapted to extend radially .through one wall of the piston boss and into a registering wrist pin aperture, said aperture opening into the wrist pin bore, releasable means associated with said looking pin and arranged within the wrist pin bore, said means being adapted to engage the wrist pin in a manner to hold the locking pin against withdrawal, and `vieldable means for holding said releasable means in engagement with the wrist pin.

2. A device for locking a hollow wrist pin in a piston boss, the pin and boss having radially extending, registering apertures, the boss aperture opening to the exterior of the boss and the wrist pin aperture opening to the wrist pine bore, a tubular locking pin adapted to be entered through the boss aperture and to engage the wrist pin, a longitudinally slidable plunger within the bore of the llocking pin and extending into the wrist pin bore, releasable means within the wrist pin bore for holding the plunger against withdrawal, and yieldable means between the locking pin and plunger for maintaining the locking pin in engagement with the wrist pin.

n. A device for locking a hollow wrist pin in a piston boss, the pin andboss having radially extending, registering apertures, the boss aperture opening to the exterior ot' the boss and the wrist pin aperture opening to the wrist pin bore, a tubular locking pin adapted to be entered through the boss aperture and having a tapered extremity adapted to seat within the wrist pin aperture, a longitudinally slidable plunger within the bore of the locking pin and extending into the wrist pin bore, releasable means within the wrist pin bore for holdin@ the plunger against withdrawal, and yielda le means between the locking pin and plunger for maintaining the tapered extremity of the locking pin seated within the wrist pin aperture.

4.. .A device for locking a hollow wrist pin the pin and boss having radially extending, registering apertures, the boss aperture opening to the exterior of the boss and the wrist pin aperture opening to the wrist pin bore, a tubular locking pin adapted to be entered through the boss aperture and having a tapered extremity adapted to seat within the wrist pin aperture, a longitudinally slidable plunger within the bore or' the locking pin and extending into i the wrist pin bore, a releasable key for the `plunger and adapted to engage the inner wall of the wrist pin at the sides .of the Wrist the pin and plunger adapted to maintain said key in engagement with the wrist pin and to maintain the tapered extremity oit the locking pin seated within the wrist aperture. y

5. A device for locking a hollow wrist pin in a piston boss, the pin and boss having radially extending, registering apertures, the boss aperture opening to the exterior of the boss andthe wrist pin aperture opening to the wrist pine bore, a tubular locking pin adapted to be entered through the boss aperture and to engage the wrist pin, a longitudinally slidable plunger within the bore of the locking pin and extending into the wrist pin bore, a releasable key 'for the plunger' and adapted to engage the delining wall of pin the wrist pin bore, and spring means con-.

necting the locking pin and plunger in a manner to maintain the plunger and key .in assembly and to maintain said locking pin in engagement with said wrist pin.

G. A device for locking a hollow wrist pin inl a piston boss, the pin and boss having radially extending, registering apertures, the boss aperture opening to the exterior of the boss and the wrist pin aperture opening to the wrist pin bore, a tubular locking pin adapted to be entered through the boss aperture and to engage the wrist pin,`al longitudinally slidable plunger within the bore of the locking pi n and extending into the wrist pin bore, a head on the extension ot the plunger, a removable key adapted to coact with said head and the wrist pin in a manner to hold the plunger from withdrawal trom the wrist piu bore, and spring means4 connecting the locking pin and plunger to maintain the plunger' and key in assembly and to maintain said locking pin in engagement with the wrist pin.

7. A device for locking a hollow wrist pin in a piston boss, the pin and boss having radially extending, registering apertures, the boss aperture opening` to the exterior ot the boss and the wrist pin aperture opening to the wrist pin bore, a tubular locking pin adapted to be entered through the boss aperture and having a tapered extremity adapted to seat within the wrist pin aperture', a longitudinally slidable plunger within the bore oi the locking pin and extending` into the wrist pin bore, a head on the extension of the plunger, a removable key adapted to coact with said headv and the wrist pin in a manner to `hold the plunger from withdrawal from the wrist pin bore, and spring means connecting the locking pin and plunger to maintain the plunger and key in assembly and to maintain the tapered extrem- `ity of the locking pin seated within the wrist pin aperture.

k8. A device for locking a wrist pin in a piston boss, the pin and boss having radially extending7 registering apertures, the hose aperture opening Vto the exterior of lthe boss, a tubular looking pin adapted to be entered through the boss aperture and to engage the Wrist pin, a longitudinally slidahle plunger Within the bore of the locking pin and extending-into the Wrist pin aperture, releasalole means for holding the plunger against Withdrawal, and yieldable means between memos? thefloelng pin and plunger for maintain- 10 ing the loeking'pin in engagement with the wrist pin. f i

In Witness that We elailn the foregoing We have hereunto subscribed our naines this 19 day of September- 1924.

:PAUL e. u'TAGNER. ARTHUR ANDERSEN. 

